It is known in the case of optical elements that have an optical coating on their main body that the optical coating can cause compressive or tensile stresses. The thicker the optical coating, and in particular the greater the number of layers of the optical coating, the greater the stress that is caused. These stresses lead to deformations of the main body, which can for example be manifested as wavefront deformations.
In the case of optical elements of a cuboidal construction, such as for instance Fabry-Perot interferometers, it is known for example from the article by Marie-Maude de Denus-Baillargeon et al., Applied Optics, volume 53, No. 12, pages 2616ff. either to optimize the optical coating itself to the extent that the stress exerted by it is as small as possible or in the simplest case to apply an identical coating to the side opposite from the coated side, so that the stresses cancel one another out. Among the ways in which the authors seek to find suitable coatings is to resort to methods of calculation of the finite element method.
It is known from U.S. Pat. No. 8,848,167 in the case of optical elements for UV or EUV lithography that have a functional coating on a first side of a substrate likewise to provide on a second side that has a common edge with the first side a coating of a thickness and stress chosen such that the quotient of the product of the thickness and stress of the functional coating divided by the thickness and stress of the coating of the second side lies in a range of values between 0.8 and 5.0. In particular, all sides that share a common edge with the first edge are coated for stress compensation.